Breaking News
<<   <   Page 3 / 4   >   >>
User Rank
Rookie
re: Selecting a solar energy conversion method
7/9/2012 8:36:44 PM
NO RATINGS
You have stated “As the cell voltage rises, the current in the internal diode rises, leaving less of the photo current for the load”. This is not so. If you follow the panel I-V curve shown in Figure 6 when the cell voltage increases the cell current decreases. The maximum cell voltage is the open circuit voltage, Voc, where the current is zero.

User Rank
Rookie
re: Selecting a solar energy conversion method
7/9/2012 8:35:36 PM
NO RATINGS
The maximum power available from the panel does not change but the power that is actually extracted from the panel does change and it is a function of the load resistance RL. This maximum power point occurs when RL = Rs. The boost converter decreases the value of RL by adjusting its duty cycle. The input resistance seen by the panel is RL x (1-du)^2 where du is the duty cycle internally set by the SPV1020. The SPV1020 duty cycle is internally adjusted so that RL x (1-du)^2 equals the panel output resistance Rs.

User Rank
Rookie
re: Selecting a solar energy conversion method
7/9/2012 8:34:29 PM
NO RATINGS
You are correct. The intent of using the Thevenin equivalent is to show that whatever the value Rs even though non-linear, RL must match it to provide maximum power transfer.

User Rank
Rookie
re: Selecting a solar energy conversion method
7/9/2012 8:33:35 PM
NO RATINGS
RL will normally be much greater than Rs. Interposing the SPV1020 boost converter between the panel and RL decreases the load resistance seen by the panel. The load resistance seen by the panel Rin = RL x (1-du)^2 where du is the duty cycle internally set by SPV1020. The duty cycle is set by the SPV1020 so that RL x (1-du)^2 = Rs, the source resistance of the panel.

User Rank
Rookie
re: Selecting a solar energy conversion method
7/7/2012 6:29:49 PM
NO RATINGS
A very nice article with good technical details! Very much appreciated, thank you! I am wondering if this level of complexity is needed when using solar power both locally and not at normal line voltages (ie. 12V or 24V DC lighting/systems)?

User Rank
Rookie
re: Selecting a solar energy conversion method
7/7/2012 2:40:06 PM
NO RATINGS
I see that my understanding is slowly beginning to clear. I found the found Fig. 3.7 on pg. 24 of the following article to be helpful: https://digital.library.txstate.edu/bitstream/handle/10877/3171/fulltext.pdf I think what was bothering me was that the boost converter cannot increase the load voltage to any arbitrarily high level. It is necessarily limited by the PV maximum power curve for a given set of conditions (illumination, temp., etc.) This Fig. (3.7) seems to bear that out that.

User Rank
Rookie
re: Selecting a solar energy conversion method
7/6/2012 8:14:28 PM
NO RATINGS
Yes, the Thevenin model applies in figure 2, as you are looking back into the terminals of the source. What's more, if you apply a variable resistive load, you will get a linear graph of voltage vs current.

User Rank
Rookie
re: Selecting a solar energy conversion method
7/6/2012 7:39:23 PM
NO RATINGS
"Southern Exposure is Obvious" That is true only in the Northern Hemisphere. A better statement, might be "Equatorial Exposure is required"

User Rank
Rookie
re: Selecting a solar energy conversion method
7/6/2012 9:50:45 AM
NO RATINGS
Rich - as far as I am aware the panel output is surprisingly constant with time. Most panels are guaranteed more than 90% rated output after 10 years and more than 80% output after 25 years (approx 100,000 hours of daylight use). Typical results are better than that, so degradation is just a fraction of 1% per year.

User Rank
Rookie
re: Selecting a solar energy conversion method
7/5/2012 10:30:41 PM
NO RATINGS
Thevenin is a poor approach, a better model is a current source, with a parallel clamp diode, and better curves would include constant power profiles (V*I = constants) which makes the MPPT seeking easier to visualize.

<<   <   Page 3 / 4   >   >>

Flash Poll

#### Datasheets.com Parts Search

##### 185 million searchable parts (please enter a part number or hit search to begin)
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More

I remember when the first iPad came out deep in the mists of time we used to call 2010. Actually, that's only four years ago, but it seems like a lifetime away -- I mean; can you remember ...

latest comment David Ashton
Betajet">

The Circle – The Future's Imperfect in the Present Tense 5 comments
The Circle, a satirical, dystopian novel published in 2013 by San Francisco-based writer Dave Eggers, is about a large, very powerful technology company that combines aspects of Google, ...

Vincent Valentine is a man on a mission. He wants to make the first house to ever have a telephone into a telephone museum. Without help, it may not happen.

As every developer knows, there are the paper specifications for a product design, and then there are the real requirements. The paper specs are dry, bland, and rigidly numeric, making ...

latest comment MWagner_MA
Special Video Section
The LT8640 is a 42V, 5A synchronous step-down regulator ...
5:52
The LTC2000 high-speed DAC has low noise and excellent ...
5:14
How do you protect the load and ensure output continues to ...
6:54
General-purpose DACs have applications in instrumentation, ...
7:34
Linear Technology demonstrates its latest measurement ...
10:29
Demos from Maxim Integrated at Electronica 2014 show ...
4:17
Bosch CEO Stefan Finkbeiner shows off latest combo and ...
5:59
STMicroelectronics demoed this simple gesture control ...
2:15
Keysight shows you what signals lurk in real-time at 510MHz ...
4:17
TE Connectivity's clear-plastic, full-size model car shows ...
3:42
Why culture makes Linear Tech a winner.
6:08
Recently formed Architects of Modern Power consortium ...
6:39
Specially modified Corvette C7 Stingray responds to ex Indy ...
8:52
Avago’s ACPL-K30T is the first solid-state driver qualified ...
2:42
NXP launches its line of multi-gate, multifunction, ...
4:56
Doug Bailey, VP of marketing at Power Integrations, gives a ...
9:28
See how to ease software bring-up with DesignWare IP ...
5:19
DesignWare IP Prototyping Kits enable fast software ...
4:01
This video explores the LT3086, a new member of our LDO+ ...
7:03
In today’s modern electronic systems, the need for power ...
5:48